Endomembrane system
A linked set of membrane compartments that make, sort and ship proteins and lipids. It includes the rough ER, smooth ER, Golgi apparatus, lysosomes and vesicles.
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Analogy
A factory line with a packing and postage department at the end.
In practice
A hormone such as insulin is built on rough ER, packaged by the Golgi, and shipped out in vesicles.
Practice
Flashcards
- Where are proteins for export made and packaged?Made on rough ER, then modified and packaged in the Golgi apparatus.
Questions people ask
What is the difference between rough and smooth ER?
Rough ER is studded with ribosomes and makes proteins that will be secreted or placed in membranes. Smooth ER has no ribosomes. It makes lipids, stores calcium ions and breaks down some toxins, which is why liver cells have plenty of it.
What does the Golgi apparatus actually do?
The Golgi receives proteins from the ER, modifies them (for example by adding sugar chains), sorts them and sends them out in vesicles. It works like a post office: it labels each package with a signal and sends it to the lysosome, the membrane or outside the cell.